To develop indigenous alternative and renewable energy resources, long-term subsidy programs (1986–1991 and 2000–present) for solar water heaters have been enforced in Taiwan. By the end of 2010, the total installed area of solar collectors had exceeded 2 million square meters. However, over 98% of solar water heaters were used in residential systems for hot water production, with the areas of installed solar collector being less than 10 square meters. There were only 98 systems with area of solar collectors installed exceeding 100 square meters put into operation from 2001 to 2010. These systems were mainly installed for water heating in dormitories, swimming pools, restaurants, and manufacturing plants. In the present study, a comprehensive survey of these large-scale solar water heaters was conducted. The objectives of the survey were to assess the system performance and to collect feedback from individual users. It is found that lack of experience in system design and maintenance are the key factors affecting reliable operation of a system. Hourly, daily and long-term field measurements of a dormitory system were also examined to evaluate its thermal efficiencies. Results indicated that thermal efficiency of the system is associated with the daily solar radiation. Hot water use pattern and operation of auxiliary heater should be taken into account in system design.

In response to the impact of the United Nations Framework Convention on Climate Change, developing and using renewable energy sources and technologies have become vital for managing energy supply and demand in Taiwan. The long-term subsidy programs (1986–1991, 2000–present) for solar water heaters (SWHs) launched by the Taiwanese government constitute the main driving force for market expansion. By the end of 2013, the cumulative area of installed solar collectors was 2.27 million m². Approximately 0.3 million systems (or 1.545 million m²) are in operation. This corresponds to an annual collector yield of 0.92 TWh, which is equivalent to savings of 98.7 thousand tons of oil and 319 thousand tons of CO_2,eq. The market-driven mechanism is associated with cost-to-benefit ratios, construction businesses, types of building architecture, degree of urbanization and household composition. The strong wind load of typhoons is another major concern. For sustaining the solar thermal industry in Taiwan, the dominant factor for disseminating SWHs in metropolitan areas involves developing building-integrated solar thermal systems. Alternative financial incentives are required for industrial heating processes in the commercial sector.

Government intervention in the form of financial incentives is crucial for translating customer choice into a larger market share for solar thermal applications. The lengthy subsidy programs for solar water heaters in Taiwan have expanded the local market. On a remote island (Kinmen County), the area of solar collectors that are installed per 1000 inhabitants is 192.9 square meters. This study investigates a market-driven mechanism in terms of disposable income, household structure, building type and financial viability. The dual subsidy programs appear to have distorted the local market. The cumulative energy savings for solar water heaters that are installed is misleading because the systems are over-designed and there is a high replacement rate (or shorter service period).

This study determines the energy usage pattern for Penghu, which is an island in the Taiwan Strait, for which electricity is the major energy source. There is an increase in electricity consumption as the number of inhabitants and tourists increases. Water supply from desalination plants represents another major electricity demand. To reduce energy consumption and carbon emissions, subsidy programs are used to encourage the use of LED lighting and energy-efficient appliances (air conditioners and refrigerators), but not for common appliances, such as chest freezers. Abundant solar radiation in summer and the northeast monsoon in autumn/winter make Penghu an ideal location to take advantage of solar energy and wind power. An undersea cable between Penghu and Taiwan is now available and can be used to stabilize the isolated grid system in Penghu. The target for a low-carbon island can be achieved by installing PV systems and onshore and offshore wind turbines to fulfill the energy demand for the tourism industry.

Solar water heaters represent the success story in the development of renewable energy in Taiwan. With increasing public awareness, there are over 0.3 million residential systems in operation. To disseminate solar water heaters in remote islands, economic feasibility and water quality are taken into account in this study. The payback period in Kinmen and Penghu Counties are evaluated, according to effective annual solar energy gain, hot water consumption pattern and cost. Assessment of the scaling and corrosion tendencies for solar water heaters using tap and underground water are also presented. For flat-plate solar collectors with metal components, favorable corrosion resistance and protective anti-corrosion coatings are required.

A field study was conducted through interviews on offshore islands in Taiwan to investigate the energy usage of local residents. A comparison of household appliance usage in mainland Taiwan with that on the offshore islands revealed that, overall, the most commonly used household appliances are steam cookers/rice cookers, water dispensers, and washing machines. For other household appliances, Levels 2 and 3 offshore isles have lower use penetration rates compared with those in mainland Taiwan and on Level 1 offshore isles, particularly for the use of computers. By contrast, the use penetration rate for chest freezers on Levels 2 and 3 offshore isles is high, and each household has one or more freezers on average. This appliance is not a commonly observed household product in mainland Taiwan or on Level 1 offshore isles. Furthermore, because of the government policy, every household on parts of Level 2 offshore isles and on all Level 3 offshore isles has a fixed monthly charge of electricity. The transportation of liquefied petroleum gas is also inconvenient, and the gas price is slightly higher, leading to the tendency of residents to consume excessive amounts of electrical energy, which does not correspond with the aim of the government to conserve energy and reduce carbon emissions; thus, the relevant authorities’ review and improvement on energy consumption on Levels 2 and 3 offshore isles are required.